1. Field of the Invention
The present invention relates to a sublimation transfer ink jet recording method and an ink composition for the same.
2. Background Art
Ink jet recording is a method wherein ink droplets are ejected through fine nozzles to record letters or figures onto the surface of a recording medium. Ink jet recording methods are roughly classified into two types. The first type is a continuous type wherein a strong electric field is applied between a nozzle and an electrode provided ahead of the nozzle to regulate the impact position of the ink. This type has been mainly used in industrial applications. The second type is a drop-on-demand type which, in recent years, has become extensively used in ink jet printers. This type has been put to practical use as a method wherein an electric signal is converted by means of an electrostriction element to a mechanical signal which selectively ejects ink reservoired in a nozzle head portion to record letters or symbols on the surface of a recording medium and a method wherein ink, reservoired in the nozzle head, in its portion very close to the ejection portion is rapidly heated to evolve bubbles and, by taking advantage of volume expansion of the bubbles, the ink is intermittently ejected to record letters or symbols onto the surface of the recording medium.
Application of this ink jet recording method to sublimation textile printing or sublimation transfer printing has been proposed in the art.
For example, Japanese Patent Publication No. 42317/1985 discloses a method wherein an ink containing a sublimation dye and triethylene glycol is printed by ink jet recording onto a support having thereon an ink penetration preventive layer to form a transfer image which is then put on a receptor object, such as a polyester fiber, followed by heat treatment to transfer the image onto the receptor object.
U.S. Pat. No. 5,488,907 discloses a method wherein an ink comprising a heat-active dye, at least one emulsifying enforcing agent for shielding the dye, and at least one solvent is printed onto a recording medium by ink jet recording to form thereon an image which is then heated to the activation temperature of the heat-active dye or above to transfer the image onto an object.
In recent years, there has been remarkable technical innovation in ink jet recording, particularly drop-on-demand type ink jet recording. For example, an increase in resolution of printed images by increasing the density of ink ejection head nozzles and an increase in image writing speed by adopting a multi-nozzle system or by increasing the ink ejection frequency have been attempted. Therefore, ink compositions, which can cope with increased resolution and increased speed, are also required of the sublimation transfer ink jet recording method.
The present inventors have now found that an ink composition having a specific composition, when used with sublimation transfer ink jet recording, can realize the formation of high-quality images on receptor objects. More specifically, the present inventors have found an ink composition which has good ejection stability and, at the same time, can realize good dye transferred images.
Accordingly, it is an object of the present invention to provide an ink composition which can satisfy, on a high level, various property requirements required of ink compositions for ink jet recording (for example, properties such as excellent ejection stability and capability of realizing images free from feathering or color-to-color bleeding) and, at the same time, upon sublimation transfer of the image yielded by the ink composition, can realize good dye transferred images.
It is another object of the present invention to provide a sublimation transfer ink jet recording method which can realize good images.
According to one aspect of the present invention, there is provided an ink composition for use in a sublimation transfer ink jet recording method, comprising at least a heat transferable dye, a glycol ether, an acetylene glycol surfactant, and water.
According to another aspect of the present invention, there is provided a sublimation transfer ink jet recording method comprising the steps of: printing an ink composition containing a heat transferable dye by ink jet recording onto an intermediate transfer medium to form a latent image on the intermediate transfer medium; putting the intermediate transfer medium on the surface of a receptor object; and heating the intermediate transfer medium at a sufficient temperature and for a sufficient time to sublimate the heat transferable dye and to deposit the sublimated dye onto the surface of the receptor object, the ink composition being the above ink composition of the present invention.
Ink Composition
The ink composition of the present invention comprises at least a heat transferable dye, a glycol ether, an acetylene glycol surfactant, and water.
Heat Transferable Dye
The details of a sublimation transfer method using the ink composition according to the present invention are as described below. This method is the application of a carrier dyeing method using a disperse dye, wherein molecular gaps of fibers are increased and the fibers are colored with a dye by utilizing van der Waals force or hydrogen bond force. Therefore, according to the present invention, the heat transferable dye is preferably a disperse dye. In addition to disperse dyes, some of azoic dyes, vat dyes, or cationic dyes can be utilized in the present invention so far as sublimation transfer can be carried out in a proper temperature range.
Examples of preferred heat transferable dyes include disperse dyes, such as (1) C.I. Disperse Yellow 1, 3, 4, 5, 7, 8, 31, 33, 39, 42, 54, 60, 61, 64, 83, and 124, (2) C.I. Disperse Red 1, 4, 5, 7, 11, 12, 13, 15, 17, 31, 32, 33, 34, 35, 36, 52, 54, 55, 56, 58, 60, 72, 73, 76, 80, 84, 88, 91, 92, 93, 99, 111, 113, 135, 204, 205, 206, 207, 224, 225, 227, 239, and 240, and (3) C.I. Disperse Blue 20, 26, 54, 55, 56, 58, 60, 61, 62, 64, 72, 79, 81, 85, 87, 90, 91, 92, 94, 97, 98, 99, 103, 104, 105, 106, 108, 128, 148, 149, 176, 186, 187, 193, 194, 195, 197, 201, 205, 207, 211, 212, 213, 214, 215, 216, 217, 218, 219, 220, 221, 222, 223, 224, 225, 226, and 227. Vat dyes as other examples of dyes include C.I. Vat Red 41.
As the heat transferable black dye, a mixed disperse dye is preferred.
The ink composition according to the present invention contains an acetylene glycol surfactant. The addition of the acetylene glycol surfactant has the effect of reducing the foaming of the ink. Therefore, according to the present invention, the use of the acetylene glycol surfactant can reduce a failure, of the ink ejection head to eject ink, derived from the occurrence of foams within the head. Further, the acetylene glycol surfactant, in combination with a glycol ether solvent described below, can enhance the penetration of the ink into recording paper and, at the same time, can prevent uneven bleeding of images (color-to-color bleeding).
Examples of preferred acetylene glycol surfactants include Surfynol 104, 420, 440, 465, 485, 504, 61, DF-110D, DF-210, DF-37, DF-58, DF-75, SF-F, TG, GA, CT-111, CT-136, CT-151, PSA-204, PSA-216, PSA-336, OP-340, OP-350, 104S, and DF-110S (all the above products being manufactured by Air Products and Chemicals Inc.). Various types of Surfynol ranging from water-soluble types to oleaginous types are available. According to the present invention, preferably, the type of Surfynol and the amount thereof added are properly determined from the viewpoints of regulating the penetration of the ink into the paper, the wettability of the ink ejection head in its nozzle face, and stable dissolution of Surfynol in the ink. The amount of Surfynol added is generally about 0.01 to 5% by weight, preferably about 0.1 to 3% by weight.
The ink composition according to the present invention contains a glycol ether. The glycol ether, in combination with the acetylene glycol surfactant, can enhance the penetration of the ink into recording paper and, at the same time, can prevent uneven bleeding of images (color-to-color bleeding).
Examples of preferred glycol ethers, which are contained in the ink composition for ink jet recording according to the present invention, include di- or tri-ethylene glycol monobutyl ether, mono- or di-propylene glycol monobutyl ether, di- or tri-ethylene glycol mono-pentyl or -hexyl ether, propylene glycol mono- or di-ethylene glycol mono-butyl, -pentyl, or -hexyl ether, and ethylene glycol mono- or di-propylene glycol mono-butyl, -pentyl, or -hexyl ether. They may be used alone or as a mixture of two or more.
The glycol ether has low water solubility. Therefore,when the amount of the glycol ether added is large, the glycol ether sometimes causes phase separation at room temperature. In this case, the glycol ether cannot be added in a large amount to the ink. when highly water-soluble glycol ether or an organic solvent is added simultaneously with the glycol ether, the amount of the glycol ether having low water solubility added can be increased.
Although the amount of the glycol ether added may be properly determined, the amount is preferably about 5 to 20% by weight. The above amount of the glycol ether can ensure good penetration of the ink composition into the intermediate transfer medium (for example, paper). In addition, the ink composition can be easily brought to a viscosity suitable for ink jet recording.
Further, various water-soluble surfactants may be added to the ink composition according to the present invention from the viewpoint of controlling the penetration of the ink composition, enhancing the stability of the heat transferable dye, or improving the solubility of the acetylene glycol surfactant and the glycol ether in the ink.
Specific Examples of water-soluble surfactants include: ether surfactants, such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkylallyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyalkylene alkyl ether; polyoxyethyleneoleic acid; ester surfactants, such as polyoxyethyleneoleic ester, polyoxyethylenedistearic ester, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; and fluorosurfactants, such as fluoroalkyl esters and salts of perfluoroalkylcarboxylic acids.
The amount of the water-soluble surfactant added is preferably not more than 3% by weight. The above amount of the water-soluble surfactant can effectively suppress the foaming of the ink composition and the thickening of the ink. In addition, unstable ejection caused by uneven wetting of the ink ejection head in its nozzles can be effectively prevented.
Further, the ink composition according to the present invention may further contain a water-soluble glycol from the viewpoint of preventing nozzle clogging caused by drying. Examples of preferred glycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol having a molecular weight of not more than 2,000, 1,3-propylene glycol, isopropyleneglycol, isobutyleneglycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, glycerin, and pentaerythritol.
The ink composition according to the present invention may further contain a saccharide for the same purpose as in the addition of the water-soluble glycol. Saccharides usable herein monosaccharides and polysaccharides. Specific examples thereof include glucose, fructose, ribose, xylose, arabinose, lactose, galactose, maltose, cellobiose, sucrose, trehalose, and maltotriose. Further, alginic acid and salts thereof, cyclodextrins, and celluloses may also be used as the saccharides. The amount of the saccharide added is preferably 0.05 to 20% by weight. The above amount of the saccharide added can effectively prevent the nozzle clogging. In addition, the ink composition can be easily brought to a proper viscosity range. The amounts of the monosaccharide and the polysaccharide (for example, glucose, fructose, ribose, xylose, arabinose, lactose, galactose, maltose, cellobiose, sucrose, trehalose, or maltotriose) added are more preferably 3 to 10% by weight. The use of alginic acid and salts thereof, cyclodextrins, and celluloses in a certain amount sometimes brings about excessively high viscosity of the ink composition, and, thus, care should be taken in the addition of these materials so as not to cause this unfavorable phenomenon.
If necessary, the ink composition according to the present invention may further comprise other additives, and examples of other additives usable herein include preservatives, antimold, antioxidants, electric conductivity adjustors, pH adjustors, viscosity modifiers, surface tension modifiers, oxygen absorbers, and/or nozzle clogging preventives. The type of the additives used may be properly determined. For example, when the use of preservatives or antimold is desired, sodium benzoate, pentachlorophenol sodium, 2-pyridinethiol-1-oxide sodium, sodium sorbate, sodium dehydroacetate, and/or 1,2-dibenzothiazoline-3-one (Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, and Proxel TN, manufactured by ICI) may be used.
The ink composition according to the present invention preferably has a surface tension of 20 to 40 mN/m at 5 to 45xc2x0 C. The temperature 5 to 45xc2x0 C. is the actual service temperature of printers, and the surface tension in the above range can realize stable printing and, in addition, can effectively suppress feathering or color-to-color bleeding of images.
The ink composition according to the present invention preferably has a viscosity of 2 to 10 mPaxc2x7s at 5 to 45xc2x0 C. The viscosity that is in the above range can realize a printing free from an ink droplet trajectory directionality problem. Further, the ink composition can be printed by ink jet recording with good energy efficiency.
Sublimation Transfer Ink Jet Recording
The ink composition according to the present invention is used in sublimation transfer ink jet recording. The sublimation transfer ink jet recording method comprises the steps of: printing an ink composition containing a heat transferable dye by ink jet recording onto an intermediate transfer medium to form a latent image on the intermediate transfer medium; putting the intermediate transfer medium on the surface of a receptor object; and heating the intermediate transfer medium at a sufficient temperature and for a sufficient time to sublimate the heat transferable dye and to deposit the sublimated dye onto the surface of the receptor object.
According to the present invention, the intermediate transfer medium is not particularly limited so far as it can hold thereon a latent image yielded by the ink composition and can realize good sublimation transfer onto a receptor object. However, the use of paper as the intermediate transfer medium is preferred. According to a preferred embodiment of the present invention, a specialty paper for ink jet recording, which has been produced so as to have properties suitable for use in ink jet recording, for example, provided with an ink-receptive layer, is utilized.
According to a preferred embodiment of the present invention, the intermediate transfer medium has a property such that the penetration of ink droplets, which have been deposited thereon, into the intermediate transfer medium is completed within 2 sec. The use of the ink composition and the intermediate transfer medium, which permit the penetration of the ink composition into the intermediate transfer medium to be completed within 2 sec, can realize the formation of a latent image free from significant feathering or color-to-color bleeding.
According to another preferred embodiment of the present invention, the intermediate transfer medium is paper, and the amount of the ink deposited per 5xc3x9710xe2x88x923 mm2 of the paper is not more than 160 ng. In this case, good latent images free from color mixing at the boundary areas between contiguous colors can be formed.
After a latent image is formed on the intermediate transfer medium, the intermediate transfer medium is put on, preferably brought into intimate contact with, a receptor object, followed by heating to transfer the latent image onto the receptor object.
According to the present invention, the receptor object is not particularly limited so far as the heat transferable dye is fixable thereon. Examples of receptor objects usable herein include fabrics, metals, potteries or ceramic whitewares, plastics, ceramics, and concrete substrates.
According to a preferred embodiment of the present invention, the heat transferable dye used in the present invention can color polyesters, acetates, and nylons. Therefore, the presence of the above material in the receptor object is preferred from the viewpoints of color properties and color density. The receptor object is more preferably a fabric of which more than 50% by weight has been accounted for by the above material, for example, a cotton-blended cloth. Further, according to another preferred embodiment of the present invention, the receptor object is coated with a material containing at least 50% by weight of polyester, acetate, or nylon.
According to a preferred embodiment of the present invention, not less than 10% of the total weight of the heat transferable dye in the latent image yielded on the intermediate transfer medium is transferred onto an object from the viewpoint of good color properties and color density.
The receptor object with the intermediate transfer medium put thereon is preferably heated at the heat activation temperature of the heat transferable dye or above. Many of the heat transferable dyes described above have a heat activation temperature of 100 to 200xc2x0 C. Therefore, the heating is carried out at this temperature or above, preferably at a temperature of about 120 to 160xc2x0 C. The transfer time may be properly determined. In general, however, the transfer time is preferably 10 to 300 sec, more preferably 60 to 120 sec.
Further, according to a preferred embodiment of the present invention, the step of heating comprises the steps of: after putting the intermediate transfer medium on the receptor object, heating the intermediate transfer medium and the receptor object from room temperature to the heat activation temperature of the heat transferable dye; holding the intermediate transfer medium and the receptor object at the heat activation temperature of the heat transferable dye or above; and then decreasing the temperature of the intermediate transfer medium and the receptor object from the heat activation temperature of the heat transferable dye to room temperature. According to a preferred embodiment of the present invention, from the viewpoint of realizing good transfer, the time required in the step of raising the temperature of the intermediate transfer medium and the receptor object from room temperature to the heat activation temperature of the heat transferable dye is longer than the time in the step of holding the intermediate transfer medium and the receptor object at the heat activation temperature of the heat transferable dye or above.
According to another preferred embodiment of the present invention, the heating is carried out by microwave irradiation. The microwave irradiation is advantageous in that the heating can be simply carried out by means of a microwave oven, for example, also in the home.
The sublimation transfer of the heat transferable dye by utilizing a microwave constitutes still another aspect of the present invention. Specifically, according to the present invention, there is provided a recording method comprising the steps of: printing an ink composition containing a heat transferable dye onto an intermediate transfer medium to form a latent image on the intermediate transfer medium; putting the intermediate transfer medium on the surface of a receptor object; and applying a microwave to the intermediate transfer medium for a sufficient time to sublimate the heat transferable dye and to deposit the sublimated dye onto the surface of the receptor object. According to this aspect of the present invention, ink jet recording may be used to print the ink composition onto the intermediate transfer medium. Further, according to this aspect of the present invention, prior to the application of the microwave, a moisture-retaining liquid is preferably coated onto the backside of the intermediate transfer medium with a latent image printed thereon in order to prevent the intermediate transfer medium from being excessively dried during microwave irradiation. The moisture-retaining liquid basically comprises glycerin as a humectant, a saccharide, and water.